Compact electronic apparatus and method of assembling the same

ABSTRACT

A personal computer comprises a housing having a bottom wall. A plurality of functional components are arranged side by side on the bottom wall of the housing. A fixture plate is arranged on top of the functional components and secured to the functional components and the bottom wall by means of screws. The functional components are held between the fixture plate and the bottom wall.

This is a divisional of application Ser. No. 08/107,948, filed Aug. 16,1993, now U.S. Pat. No. 5,455,746.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a portable electronic apparatus such as a bookshaped personal computer or a word processor and, more particularly, toa portable electronic apparatus comprising a synthetic resin housingcontaining therein various functional components such as a floppy discdrive, hard disc drive, and the like, and a method of assembling thesame.

2. Description of the Related Art

Recently, there are known book or notebook-shaped portable computershaving a flat box like base unit on which a keyboard and a display unitwith a flat display panel are mounted.

A portable computer of the above identified type normally comprises asynthetic resin housing that provides a frame for a base unit andcontains therein various functional components such as a floppy diskdrive and/or a hard disc drive along with circuit board carrying thereonvarious circuit components. These functional components are normallysupplied in the form of modules and placed in positions on the bottomwall of the housing, where they are then secured by means of screws tothe bottom wall.

Upon assembling the conventional portable computers of this type,however, each of the functional components placed on the bottom wall isrequired to be independently secured by screws to the bottom wall. Thus,the attachment of the components is very troublesome, and thus, theassembling of the computer takes large time periods.

Further, the bottom wall of such a housing has a rather complicatedprofile because bosses for receiving screws should be provided on thebottom wall at positions on which functional components are placed.These bosses inevitably reduce the space inside the housing that canotherwise be used to accommodate components. In recent portablecomputers, it is desired that the housing is reduced in size in order toimprove the portability of the computer. However, if the mounting spacein the housing is reduced by the bosses, it is necessary to increase thesize of the housing so as to increase the mounting space thereof, whichopposes the requirement for providing a compact computer.

In addition to the various functional components, the housing of aportable computer contains therein a circuit board on which variouscircuit components are mounted. This circuit board normally has arectangular shape substantially corresponding to the size of the bottomwall of the housing. So the space on the bottom wall is substantiallyoccupied by the circuit board.

In order to improve the portability of the recent computers, it isrequired to reduce the length and the width of the housing. Thus, themounting space in the housing tends to be further reduced in size, andforces the circuit board to be made further smaller. For solving thisproblem, there is proposed an arrangement wherein a single relativelylarge circuit board is divided into a plurality of small parts. Thedivided board are arranged in the housing such that they are overlappedwith one another and connected to one another by means of flexibleconnecting boards.

Some of the circuit components carried by the circuit boards generatehigh frequency noises during operation. Such high frequency noises caninterfere with wired as well as wireless telecommunications when leakout of the housing. Therefore, in conventional portable computers, theinner surface the housing of is normally coated with a conductive layertypically by plating so as to provide the housing with anelectro-magnetic shield effect. The circuit boards and other electroniccomponents of the computer are enclosed with the conductive layer.

with such an arrangement, however, the circuit boards are apt to moverelative to each other as they are connected together by flexibleconnecting boards, making the mutual connection of the boards unstable.This means that, when securing one of the circuit boards to the housing,it may accidentally shake the other circuit boards connected to it,causing them to hit and damage the conductive layer on the inner surfaceof the housing with their corners and edges and/or the componentscarried on them until eventually the conductive layer partly comes offfrom the cabinet and loses its electro-magnetic shield effect.

In order to avoid such problem, it is necessary to carefully assemblethe circuit board in the housing, thereby making the assemblytroublesome. Additionally, the housing needs to be provided with a largenumber of bosses for screws for securing a plurality of circuit boardsto the housing in a multilayered manner. Such additional bosses make thehousing even more rugged and the efficiency of assembling a portablecomputer by using such a large number of screws to be driven into arugged housing is inevitably low.

In a portable computer of the type under consideration, if a userdesires to use application software and/or an application device, it isoften required to be modified the computer by arranging additionalcomponents on the circuit substrates and/or replacing some of theexisting components with improved ones in accordance with theapplication software and/or the application devices to be used. Themultilayer arrangement of a plurality of circuit boards as describedabove then needs to be so devised as to facilitate such addition and/orreplacement of circuit components without being disturbed by the circuitboards.

A portable computer of the above mentioned type is normally providedwith a rechargeable battery pack for supplying power to the computereven when no commercial power supply is available. Such a battery packmay need replacement when it is time worn and has lost itsrechargeability and therefore it is normally removably fitted to thebase unit. In other words, the base unit of a conventional portablecomputer is provided with a storing space for storing a battery pack anda manually releasable lock mechanism for locking the battery pack in thestoring space.

The lock mechanism comprises a knob with which the operator of thecomputer can control it by using a finger tip. The knob is usuallyexposed at a lateral side or the bottom of the base unit. The operatorcan release the lock mechanism by sliding the knob sideways with afinger tip and take the battery pack out of the base unit.

If the knob is exposed outside the housing, although it may be easilyoperable, it is subject to the danger of accidental release of the lockmechanism. Although the problem may be avoided by arranging a knob coveron the base unit, the provision of the knob cover gives rise to anotherproblem of requiring a two-step operation of opening the cover orholding it in a position for exposing the knob and then sliding the knobbefore taking out the battery pack.

Furthermore, once the battery pack is recharged or replaced and put backin position, the knob cover needs to be slid back or reattached to thebase unit, imposing an additional manual work on the operator. If theknob cover is not returned to its proper position, on the other hand,the knob remains in an exposed condition, leaving the lock mechanismunprotected against improper handling.

Portable computers are generally provided with expansion slots forreceiving so-called expansion substrates for expansion features. In linewith the recent trend of using card-shaped standardized substrates forexpansion features, the PC Memory Card International Association(PCMCIA) in the U.S.A. has proposed four types of standardized cards aslisted below.

Type 1: thickness 3.3 mm; type 2: thickness 5.0 mm; type 3: thickness10.5 mm; thick type: thickness 18.00 mm.

Cards of types 1 and 2 are mostly used for IC memory cards that carrysemiconductor memories thereon and find a variety of applicationsincluding those of security cards and cards of type 3 are often used assmall card discs for I/O features, whereas cards of thick type findapplications including those of I/O, LAN (local Area Network), FAX andmodem features.

However, the fact that the PCMCIA has proposed such diverse standardsclearly shows how standardization is difficult for cards of the sortdiscussed above. Particularly where portable electronic apparatuses needto meet the requirement of downsizing, it is extremely difficult toprovide housings that are compatible with all standardized cards and atthe same time satisfy the requirement of reduced outer dimensions ofapparatus.

SUMMARY OF THE INVENTION

In view of the above described circumstances, it is therefore an objectof the present invention to provide a portable electronic apparatus anda method of assembling the same, wherein a plurality of functionalcomponents can be easily placed in and fixed to the housing with asingle operation to facilitate the overall assembling operation.

It is another object of the invention to provide a portable electronicapparatus wherein a housing has a simple profile that allows functionalcomponents to be installed in a highly space saving manner withoutenlarging the dimensions of the housing.

It is still another object of the invention to provide a portableelectronic apparatus wherein synthetic resin components and metalcomponents of the housing can be easily separated from each other sothat it may be effectively disposed as waste without damaging theenvironment as its recyclable components can be completely recoveredonce its service life is over.

It is further object of the invention to provide a portable electronicapparatus which can securely shield noises generated from electronicparts on circuit boards which are arranged in a housing in amultilayered manner, and wherein the circuit boards can be easilyinstalled in the housing, thereby facilitating the assembly of theapparatus.

It is still further object of the invention to provide a portableelectronic apparatus wherein even if a shutter for covering a lock leveris provided, the lock lever can be easily operated and is so arrangedthat, once the finger tip operating the lock lever is removed from thelatter, the shutter is automatically released from its suspendedposition and comes to cover the lock lever again, not allowing itself tobe held away from the proper position for covering the lock lever.

It is another object of the invention to provide a portable electronicapparatus capable of selectively receiving differently sized cards whichare based on a common standard.

In order to achieve the above object, a portable electronic apparatusaccording to an aspect of the present invention comprises a housinghaving a bottom wall; a plurality of functional components arranged sideby side on the bottom wall and a fixture plate arranged on thefunctional components for holding the functional components between thefixture plate and the bottom wall as the fixture plate is secured to thefunctional components and the bottom wall by means of screws.

Preferably, the bottom wall of the housing is provided with a pluralityof bosses for receiving screws.

With the portable electronic apparatus having a configuration asdescribed above, the functional components arranged on the bottom wallof the housing are rigidly secured to the housing as they are heldbetween the fixture plate and the bottom wall in a single operation and,therefore, the functional components do not need to be individuallysecured to the bottom wall with screws. Consequently, the entireoperation of assembling the portable electronic apparatus can beremarkably simplified.

If the bottom wall of the housing is provided with bosses for receivingscrews, their arrangement does not need to correspond with that of theindividual functional components and, therefore, only a small number ofscrews and hence bosses are required. Consequently, the housing issimple in structure, and that space in which conventional bosses areprovided can be made available for mounting the functional components.Thus, functional components may be placed closer to one another and thebottom wall to efficiently use the limited space defined in the housing.

Preferably, one of two adjacent functional components provided on thebottom wall of the housing includes a holding portion located over theother functional component, and the holding portion is secured to a bossof the housing. With this arrangement, any two adjacent functionalcomponents may be jointly secured to the housing cabinet, therebyreducing the number of screws required to securely hold the functionalcomponents to the housing and that of bosses to be formed on thehousing. Consequently, the housing may have a simplified profile and thetime and cost for assembling the entire apparatus will be significantlyreduced.

It is preferable for the functional components to be provided with a lugto be secured to the housing with the fixture plate by means of a screw.With such an arrangement, since each of the functional components andthe fixture plate can be secured to the housing by means of a commonscrew, the total number of screws and bosses required for the entireapparatus can be remarkably reduced.

It is also preferable that, if the functional components include circuitparts generating noises in operation, the fixture plate is made ofmetal. Then, any high frequency noises generated from any of thefunctional components can be shielded within the space defined by thefixture plate and the housing to eliminate the possibility for thenoises to interfere with wire as well as wireless telecommunications ifthey leak out of the housing.

According to another aspect of the present invention, there is provideda portable electronic apparatus comprising a synthetic resin housinghaving a bottom wall; a plurality of functional components arranged sideby side on the bottom wall and having metal parts; and a metal fixtureplate arranged on top of the functional components for holding thefunctional components between the fixture plate and the bottom wall asthe fixture plate is secured to the functional components and the bottomwall by means of screws.

With a portable electronic apparatus having an above describedconfiguration, the functional components can be removed from the housingin a single operation of unscrewing the fixture plate. Therefore, thesynthetic resin housing can be easily separated from the metal fixtureplate and the functional components having metal parts when the servicelife of the apparatus is over and the apparatus is to be disposed aswaste so that any recyclable parts of the apparatus may be recovered asresources.

According to still another aspect of the invention, there is provided amethod of assembling a portable electronic apparatus comprising thesteps of arranging a plurality of functional components, each providedas a module, on the bottom wall of a housing; laying a fixture plate ontop of said functional components; and securing the fixture plate to thehousing and the functional components by means of screws to rigidly holdthe functional components between the bottom wall of the housing and thefixture plate.

With such a method of assembling a portable electronic apparatus, aplurality of functional components can be secured to their respectiveproper positions only by the operations of laying a fixture plate on topof the functional components and securing the fixture plate to thehousing and the functional components by means of screws once thecomponents are placed in position on the bottom wall of the housing, thefunctional components do not need to be individually secured to thebottom wall as in the case of conventional assembling methods. So theoverall operation of assembling functional components and othercomponents into a portable electronic apparatus is remarkably simplifiedand therefore can be carried out in an effective and efficient manner.

According to still another aspect of the invention, there is provided aportable electronic apparatus comprising a synthetic resin housing; aplurality of rigid circuit boards arranged inside the housing one aboveanother to form a multilayered structure and carrying thereon electroniccircuits which include ones generating noises during operation; and aflexible connecting board for electrically connecting the circuitboards. The circuit boards are surrounded by a pair of shield membersand contained within the housing. The pair of shield members aresuperposed with each other and each member is provided on its surfacefacing the other member with receiving portions to which the circuitboard is fixed. The shield members are superposed while the circuitboards are fixed to the receiving portions, thereby constituting a boardunit wherein the circuit boards are held between the shield memberswhile being superposed with each other and surrounded by the shieldmembers. The board unit is enclosed in the housing.

Preferably, in order to accommodate circuit substrates arranged in threelayers within a limited space, one of the superposed shield members isprovided with an additional receiving portion projecting toward theopposite shield member beyond the first receiving portion, for receivingand securely holding another circuit board.

With such an arrangement, once the circuit substrates are secured to therespective receiving portions of the shield members and the shieldmembers are superposed with each other, the circuit boards areautomatically laid one above another to form a multilayer structure andsurrounded by the shield members.

Thus, the circuit boards that are mutually and electrically connected bymeans of flexible connecting board are arranged one above another likeso many shelves to form a unit with the shield members surrounding thembefore they are mounted on the housing so that they may be housed in thehousing without losing their safe and stable posture. Since the layeredcircuit boards are surrounded by the shield members, no additionalconductive layers are required to be arranged inside the housing toelectro-magnetically shield them. Additionally, since the shield membersformed of a metal are by far mechanically stronger than a conventionalconductive layer prepared by plating, they are least likely to bedamaged during assembly of the circuit boards into a portable electronicapparatus the shield members are, therefore capable of effectivelycontaining within them any noises that may be generated by thecomponents of the apparatus.

Since the circuit boards mutually and electrically connected by means ofa flexible connecting board are housed in the housing as a unit alongwith the shield members, it may be apparent that the housing only needsto be provided with means for rigidly holding either one of the shieldmembers. This means that the housing may have a simplified insideconfiguration as compared with a conventional housing provided withmeans for rigidly holding a plurality of circuit boards. This fact andthe fact that the circuit boards form a unit with the physically strongshield members can greatly simplify the operation of assembling thecircuit boards into a portable electronic apparatus.

Preferably, more than two of the circuit boards may be arranged on oneof the shield members in two layers. Thus, there will be formed threelayers of circuit boards that are surrounded by the shield members bysimply interposing the shield members together. Accordingly, threecircuit boards superposed with each other can be easily assembled in alimited space of the housing.

According to still another aspect of the invention, there is provided aportable electronic apparatus which comprises a housing having aperipheral wall and a storage space defined by the peripheral wall; astorage member removably stored within the storage space; manuallyreleasable lock mechanism for locking the storage member within thestorage space.

The lock mechanism includes a lock lever supported by the housing to berotatable toward and away from the storage member, the lock lever havingan engaging portion for releasably engaging the storage member and apressing portion extending in a direction opposite to that of theengaging arm with respect to the pivot of the lock lever. The lock leveris constantly urged by a first spring in a direction wherein theengaging portion engages the storage member. The housing is providedwith a window formed in the peripheral wall to expose the pressingportion of the lock lever. A shutter is arranged on the housing andslidable between a closed position where it is located between thewindow and the pressing portion of the lock lever to close the windowand an opened position where it is moved away from between the windowand the pressing portion to expose the window, the shutter being urgedtoward the closed position by a second spring. The shutter may have anedge which seizes the end of the pressing portion when the shutter ismoved to its opened position against the urging force of the secondspring.

With a lock mechanism having the above described configuration, when astorage member is stored in the storage space, the engaging portion ofthe lock lever comes to be engaged with the storage member to immovablyhold it in position. To unlock the storage member, the shutter isslidingly moved to its open position to expose the window by forciblyinserting a finger tip through the window. When the shutter is moved tothe open position, it is spaced away from the pressing portion of thelock lever. Since the lock lever is urged to rotate by the first spring,the lock lever is rotated further as the shutter is away from thepressing portion of the lock lever until the end of the pressing portioncomes right opposite the corresponding edge of the shutter. Since theshutter is urged to move toward the closed position by the secondspring, the edge of the shutter seizes the end of the pressing portionand consequently the shutter is held to the opened position to exposethe window if the finger tip is moved away from the shutter. Under thiscondition, the pressing portion of the lock lever is exposed outside thehousing through the window.

Now, if the pressing portion exposed outside through the window ispushed inward by a finger tip, the lock lever is rotated against forceof the first spring in the opposite direction until the engaging portionof the lock lever is disengaged from the storage member. Thus, thestorage member is unlocked and readily taken out of the storage space ofthe housing.

If the pressing portion is pushed, the end of the pressing portion isremoved from the edge of the shutter. So, if the finger tip pushing thepressing portion is drawn from the window and removed from the pressingportion, the shutter is forcibly pushed toward the closed position bythe second spring to close the window.

According to still another aspect of the invention, there is provided aportable electronic apparatus comprising a housing having a card slotfor storing a card of allowable maximum dimensions as defined by aselected standard; and a connector of appropriate dimensions as definedby the selected standard and arranged within the card slot.

A portable electronic apparatus having a configuration as describedabove is compatible with any cards having dimensions defined by theselected standard and, therefore, it is not necessary to provide thehousing with independent card slots corresponding to the cards. Thus,the space required for the housing to provide can be minimized.

According to a further aspect of the invention, there is provided aportable electronic apparatus comprising a housing having a first cardslot for receiving a card of allowable maximum dimensions as defined bya selected standard; and a second card slot for receiving a card ofappropriate dimensions as defined by the selected standard.

With such an arrangement, the first card slot may be used to receive acard of appropriate dimensions such as an I/O card whereas the secondcard slot may be used to receive a different card such as a securitycard that will be frequently taken out and reinserted. Therefore, twodifferent cards can be used simultaneously without significantlyincreasing the space required for the housing to provide for expansionfeatures for the apparatus. Such an apparatus will prove to beremarkably advantageous if compared with conventional apparatuses.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed out in theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate a presently preferred embodimentof the invention, and together with the general description given aboveand the detailed description of the preferred embodiment given below,serve to explain the principles of the invention.

FIGS. 1 through 32 illustrates a portable electronic apparatus accordingto an embodiment of the present invention, in which:

FIG. 1 is a schematic perspective view of the apparatus, having itsdisplay unit swung open;

FIG. 2 is an exploded perspective view of the housing;

FIG. 3 is a perspective view showing a bottom case in which functionalcomponents such as a FDD and a HDD are mounted;

FIG. 4 sectional view of a base unit, illustrating the positionalrelationship of shield plates, a board unit and the HDD of theapparatus;

FIG. 5 is a perspective view of the computer having its display unitheld in the closed position;

FIG. 6 is an exploded perspective view illustrating an area connectingthe display unit and the base unit;

FIG. 7 is a perspective view showing a battery storage section of thebottom;

FIG. 8A is a sectional view showing a state wherein a battery pack isstored in the battery storage section;

FIG. 8B is a sectional view taken along line A--A of FIG. 8A;

FIG. 9 is an exploded perspective view of a pair of shield memberssecurely holding thereon respective circuit boards;

FIG. 10 is an exploded perspective view of a first shield member;

FIG. 11 is a plan view showing a plurality of circuit boards;

FIG. 12 is a perspective view showing a shield plate and a liquidcrystal display supported in a recess of the shield plate;

FIG. 13 is an enlarged sectional view of an area of the shield platewhere the liquid crystal display is anchored;

FIG. 14 is a sectional view of first and second card slots arranged inthe housing and a cover for concealing and exposing the slots;

FIG. 15 is a schematic plan view of an expansion card;

FIG. 16 is a block diagram, illustrating the operation of the system forcontrolling the use of expansion cards;

FIG. 17 is an exploded view of the cover for concealing and exposing thecard slots;

FIG. 18 is a right-side view of the computer;

FIG. 19 is a sectional view of a third card slot and a control buttonfor operating a power switch;

FIG. 20 is a sectional view similar to FIG. 19 but showing a conditionwhere the control button is depressed;

FIG. 21 is an exploded perspective view of the control button and anarea of the bottom case where the control button is fitted;

FIG. 22 is a perspective of the control button;

FIG. 23 is a sectional view of a lock mechanism of a battery pack;

FIG. 24A is a sectional view showing a condition where the shutter isopen to expose the lock lever of the lock mechanism;

FIG. 24B is a sectional view showing a condition where the lock lever ofthe lock mechanism is pushed by a finger tip to unlock the battery pack;

FIG. 25 is a sectional view showing the positional relationship betweenthe shutter and the lock lever;

FIG. 26 is a sectional view taken along line B--B of FIG. 23;

FIG. 27 is a perspective view showing the positional relationshipbetween the shutter and the lock lever;

FIG. 28 an exploded perspective view of a structure of an expansionconnector for connecting a ball point;

FIG. 29 is a perspective view of the expansion connector fitted to thebottom case;

FIG. 30 is a sectional view of the expansion connector fitted andgrounded;

FIG. 31 is a plan view of the bottom case to which the expansionconnector is fitted; and

FIG. 32 is a perspective view of the ball point; and

FIG. 33 is a sectional view of a lock mechanism according to amodification of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, the present invention will be described with reference to theaccompanying drawing that illustrate a preferred embodiment of theinvention.

FIG. 1 shows a portable computer 1 sized to A4. The computer 1 comprisesa flat box-shaped base unit 2 and a flat panel type display unit

Housing 4 of the base unit 2 that defines the profile of the base unit 2is divided into a bottom case 5 having a top opening and a top cover 6for concealing the top opening of the bottom case 5. The bottom case 5and top cover 6 are formed of a synthetic resin material such as ABSresin.

As illustrated in FIG. 4, the bottom case 5 has a flat bottom wall 5aand a peripheral wall 5b extending from the bottom wall 5a. The topcover 6 has a substantially flat top wall 6a and a peripheral wall 6bextending from the top wall 6a. The outer surface of the peripheral wall6b of the top cover 6 is coplanarly aligned with that of the peripheralwall 5b of the bottom case 5 and the peripheral walls 5b and 6b jointlydefine the front, side and rear ends of the housing 4.

As shown in FIGS. 2 and 4, the top cover 6 is provided on its top wall6a with a large opening that serves as a keyboard outlet 7, whichsubstantially occupies the entire area of the front half of the top wall6a. The top wall 6a has a projecting portion 8 arranged at its rear end.The projecting portion 8 extends between the opposite sides of the topcover 6 and has on its underside and near the opposite ends a pair ofgrooves serving as stem bearing portions 10a, 10b and a pair of cut offareas 11a, 11b arranged adjacent to the respective stem bearing portions10a, 10b.

As seen from FIGS. 1 and 4, a keyboard unit 13 is disposed in the fronthalf area of the housing 4. The keyboard unit 13 has a keyboard body 14formed of synthetic resin and having a rectangular plate shape adaptedto fit in the keyboard outlet 7. The keyboard body 14 has a flat uppersurface and a flat lower surface and a number of keys 15 are arranged onthe upper surface. An aluminum reinforcement plate 17 is laid under thelower surface of the keyboard body 14 with a film 16 insertedtherebetween. On the film 16 is printed a circuit pattern in order totransmit switching signals generated by depressing keys. Thereinforcement plate 17 is rectangular and has a length and a width whichis the same as those of the keyboard body 14. The reinforcement plate 17serves to increase the strength of the keyboard body 14 and, at the sametime, prevent switching noises generated by key operations from leakingoutside the housing 4.

The keys 15 of the keyboard unit 13 are exposed through the keyboardoutlet 7 of the housing 4, and the reinforcement plate 17 faces insidethe housing 4.

As seen from FIGS. 1 and 6, the display unit 3 comprises a thinbox-shaped housing 20 and a liquid crystal display 21. The housing 20 isdivided into a front panel 20a and a rear panel 20b. The front panel 20ais provided with a display opening 22, through which the liquid crystaldisplay 21 is exposed. The housing 20 is provided at its opposite sideswith a pair of horizontal stems 24, 25 projecting therefrom. As shown inFIG. 6, the stem 24 is formed by combining a front stem half 24aintegrally formed with the front panel 20a and a rear stem half 24bintegrally formed with the rear panel 20b. The other stem 25 is alsoconfigured in a similar manner. The stems 24 and 25 are received by therespective stem bearing portions 10a and 10b and connected to the bottomcase 5 of the housing 4 via respective hinges 26.

Each of the hinges 26 comprises a hinge shaft 27 projecting sidewaysfrom the stems 24 or 25. As shown in FIG. 6, the hinge shaft 27 of thehinge 26 for the stem 24 is rigidly held at an end by a bracket (notshown) buried in the stem 24 and connected at the opposite end toanother bracket 28, which is rotatable around the axis of the hingeshaft 27, with a wave washer 29 interposed therebetween. The wave washer29 gives rise to frictional resistance between the bracket 28 and thehinge shaft 27 to inhibit free rotation of the hinge shaft 27, and thebracket 28 is inserted into the bottom case 5 from above and rigidlysecured to it. The above description also applies to the hinge shaft 27for the stem 25.

Thus, the hinge shafts 27 provide pivots for rotary movement of thedisplay unit 3 so that it may be rotatable to take a first positionwhere it covers the keyboard unit 13, a second position where it standsup behind the keyboard unit 13 to expose the liquid crystal display 21and a third position where the liquid crystal display 21 is found almostlying flat and opposite to the keyboard unit 13 with respect to thehinge shafts 27. In the first position as illustrated in FIG. 5, theouter surface of the housing 20 of the display unit 3 is coplanarlyaligned with that of the housing 4 including the projecting portion 8 tomake the computer 1 appear like a flat book that can be convenientlycarried by hand.

When the display unit 3 is brought to its third position 3, the topcover 6 becomes removable from the top of the bottom case 5. Under thiscondition, the hinges 26 are concealed by the projecting portion 8 ofthe top cover 6 and, if seen from outside, the stems 24, 25 appear to belocated in the respective stem bearings 10a, 10b.

As indicated in FIG. 3, a floppy disc drive (hereinafter referred to asFDD) 30, a hard disc drive (hereinafter referred to as HDD) 40 and abattery pack 50 are arranged in the above mentioned order from right toleft in the front half of the bottom case 5 as so may functionalcomponents. Each of the FDD 30, the HDD 40 and the battery pack 50 is ofmodular design and located below the keyboard unit 13.

The FDD 30 comes in a metal casing 31, which is provided on its frontend with an aperture 32 through which a floppy disc can be inserted intoand ejected from the casing 31 and a push button 33 that triggersejection of a floppy disc when it is depressed. The casing 31 is alsoprovided on its side ends with respective metal brackets 34a, 34b havingrespective lugs 35a, 35b, 36a, 36b extending upward from the top of thecasing 31.

The FDD 30 is disposed on the bottom wall 5a with the aperture 32 andthe push button 33 facing the front end of the bottom case 5 and exposedto the outside through an access opening 37 cut through the front wallof the bottom case 5 near its right side end.

As shown in FIGS. 3 and 4, the HDD 40 also comes in a metal housing 41that contains magnetic discs and heads hermetically sealed therein. Acircuit board 42 is arranged on the top of the housing 41 and variouscircuit components are mounted on the circuit board 42 to form a controlcircuit and a drive circuit for the HDD 40. The housing 41 is arrangedon the bottom wall 5a side by side with the FDD 30 and carries on itslateral wall a metal bracket 44, which by turn comprises a pair offixtures 45a, 45b that are rigidly secured to respective upright bosses47, 47 projecting from the bottom wall 5a by means of screws 46, 46.

The battery pack 50 is rechargeable and serves as power source when thecomputer 1 is used without any commercial power supply. The battery pack50 has a flat and rectangular synthetic resin case 51, which containstherein a plurality of rechargeable batteries and is arranged on thebottom wall 5a of the bottom case 5. As shown in FIGS. 3 and 7, thebottom wall 5a of the bottom case 5 carries thereon a pair of guidewalls 52a, 52a standing there to guide the sides of the case 51 anddefining a battery storage section 53 within the bottom case 5. Thebattery storage section 53 is located to the left of the bottom case 5and is accessible through a battery insertion opening 54 cut through thefront wall of the bottom case 5 near its left side end. Thus, a batterypack 50 may be inserted into and ejected from the battery storagesection 53 through the insertion opening on the front side of thehousing 4

As illustrated in FIG. 7, the battery access opening 54 includes abottom opening 54a cut through the bottom wall 5a of the bottom case 5.The front edge of the bottom wall 5a defining the rear end of the bottomopening 54a is found behind the front wall of the bottom case 5. Asshown in FIG. 8A, the case 51 of the battery pack 50 has a downwardridge 55 extending along the front end and between the opposite sideends of the case 51. The downward ridge 55 makes part of the bottom wall5a of the bottom case 5 when the battery pack 50 is inserted into thebattery storage section 53 and serves as a hook for receiving a fingertip when the battery pack 50 is pulled out of the battery storagesection 53.

As illustrated in FIGS. 8A and 8B, the battery storage section 53 isprovided along its rear end with a pair of upwardly projecting stoppers56a, 56b. As a battery pack 50 is inserted into the battery storagesection 53, its front end eventually abuts the stoppers 56a, 56b so thatthe battery pack 50 is held in position within the battery storagesection 53. On the other hand, the case 51 is provided along its frontend with positive and negative power supply terminals 57a, 57b connectedto the batteries housed in the case 51 and a pair of connector terminals58a, 58b connected to a safety fuse and a temperature sensor (notshown).

As shown in FIG. 3, a board unit 60 that operates as one of thefunctional components is housed in the rear half of the bottom case 5and is located behind the FDD 30, the HDD 40 and the battery pack 50such that it extends all the way between the opposite side ends of thebottom case 5. The board unit 60 of the embodiment comprises, as shownin FIGS. 9 and 11, first through fifth circuit boards 61a through 61eand a shield frame 62 holding and surrounding the circuit boards 61athrough 61e arranged in mutually separated three layers laid along theheight of the housing 4.

The circuit boards 61a through 61e are prepared by cutting a singlerigid board base and have appropriate respective dimensions. Each of theboards carries on its upper and lower surfaces given circuit patterns(not shown) formed by printing. As shown in FIG. 11, the circuit boards61a through 61e are divided into two groups. The first through thirdcircuit boards 61a through 61c are arranged on a side by side basisalong the transversal direction of the bottom case 5 to form a firstboard group 63, while the fourth and fifth circuit boards 61d and 61eare arranged in a similar manner to form a second board group 64. Thefirst circuit board 61a and the second circuit board 61b areelectrically connected with each other via a first flexible connectingboard 65a, whereas the first circuit board 61a and the third circuitboard 61c are electrically connected with each other via a secondflexible connecting board 65b. Similarly, the fourth circuit board 61dand the fifth circuit board 61e are electrically connected with eachother via a third flexible connecting board 65c, whereas the firstcircuit board 61 and the fourth circuit board 61d are electricallyconnected with each other via a fourth flexible connecting board 65d.Thus, while the circuit boards 61a through 61e are separated from oneanother, they are electrically mutually connected.

The circuit boards 61a through 61e carry on their upper and lowersurfaces a number of circuit components 66, which are connected to therespective circuit patterns. The circuit components 66 include thosethat generate and emit high frequency noises as well as heat.Particularly, since the third circuit board 61c in this embodimentconstitutes a power supply board, most of the circuit componentsarranged on it can generate heat at a considerable rate.

The shield frame 62 comprises a first shield plate 68, a second shieldplate 69 and a connector board 70 disposed between the shield plates 68and 69. Each of the shield plates 68 and 69 and the connector board 70is made of a metal plate having an electro-magnetic shield effect.

As illustrated in FIGS. 4, 9 and 10, the first shield plate 68 comprisesas integral parts thereof an oblong base plate section 71 to be directlyplaced on the bottom wall 5a of the bottom case 5 and an upright section72 standing from some of the edges of the base plate section 71. Thebase plate section 71 is provided with first support portions 73 forsupporting the first circuit board 61a, second support portions 74 forsupporting the second circuit board 61b and third support portions 75for supporting the third circuit board 61c. These support portions 73,74 and 75 are formed by partly cutting the base plate section 71 toproduce curved slits and bending the cut areas upward along the linesconnecting the opposite ends of the respective slits. The first andsecond support portions 73 and 74 have a substantially equal height,whereas the third support portion 75 is higher than the other twosupport portions 73 and 74.

The first and second circuit boards 61a and 61b are supportedrespectively by the front ends of the first and second support portions73 and 74 and secured thereto by means of screws. Note that the baseplate section 71 covers the undersides of the first and second circuitboards 61a and 61h and some of the circuit components 66 are arrangedbetween the base plate section 71 and the circuit board 61a or 61b. Asseen from FIG. 9, the second connecting board 65b connecting the firstcircuit board 61a and the third circuit board 61c is bent to show aturned U-shaped cross section so that the third circuit board 61c may belocated above the first and second circuit boards 61a and 61b. Moreover,the third circuit board 61c is supported by the front end of the thirdsupport portions 75 and secured thereto by means of a screw at an endopposite to the end where it is connected to the connector board 65b.Thus, it may be understood that the three circuit boards 61a through 61care arranged on the first shield plate 68 in two layers.

The base plate section 71 of the first shield plate 68 has a right sideextension 71a extending from the side of the base plate section 71located opposing to the second circuit board 61b. The extension 70a isfound behind the FDD 30 and covered by a metal plate cover 80 asillustrated in FIG. 10. The cover 80 comprises a partition 81 disposedabove the extension 71a and lugs 82 arranged on the four corners of thecover 80. The lugs 82 are respectively placed on the corners of theextension 71a and the front ends of the second support portions 74 andsecured thereto by means of screws 83.

As shown in FIGS. 3 and 9, the second shield plate 69 comprises asintegral parts thereof an oblong base plate section 85 transversallyextending on the housing 4 and an upright section 86 standing from anedge of the base plate section 85. The base plate section 85 is providedwith first support portions 87 for supporting the fourth circuit board61d and second support portions 88 for supporting the fifth circuitboard 61e. The fourth circuit board 61d and the fifth circuit board 61eare respectively secured to the front ends of the first support portions87 and the front ends of the second support portions 88 by means ofscrews.

When, as illustrated in FIG. 9, the circuit boards 61a through 61e arerespectively secured to the first and second shield plates 68 and 69,the shield plates 68 and 69 are connected to each other via the fourthconnecting board 65d. Then, the shield plates 68 and 69 are put togetheron a one on the other basis, i.e., superposed with each other, thefourth connecting board 65d being bent to show a turned U-shaped crosssection. Under this condition, the shield plates 68 and 69 are rigidlysecure to each other by means of screws (not shown). Now, the base platesection 71 of the shield plate 68 and the base plate section 85 of theshield plate 69 are oppositely located and the circuit boards 61d and61d secured to the base plate section 85 are located above the circuitboards 61a through 61c arranged on the base plate section 71. Thus, thecircuit boards 61a through 61e are arranged in three layers in thehousing 4. Note that, in this embodiment, the third circuit board 61cdedicated to power supply and hence apt to emit heat at an enhanced rateis disposed between the first circuit board 61a and the fourth circuitboard 61d.

When the shield plates 68 and 69 are put together on a one on the otherbasis, the upright sections 72 and 86 are arranged side by side toprovide the left side wall and the rear wall of the shield frame 62. Theupright sections 72 and 86 are provided with a plurality of connectoraccess apertures 92 that allows lead wires of various connectors to passtherethrough.

As shown in FIGS. 3 and 4, the connecting board 70 is disposed betweenfront end of the base plate section 71 and that of the base platesection 85 and secured to the base plate sections 71 and 85 by means ofscrews. The connecting board 70 provides the front wall of the shieldframe 62 and the fourth circuit board 61d is partly supported on the topof the connecting board 70. Near the left side end of the connectingboard 70, there is formed a slot 94 through which the front end of thebattery pack 50 is introduced. The battery pack 50 is held under an areaof the base plate section 85 located above the slot 94.

The board unit 60 comprising the circuit boards 61a through 61e and theshield frame 62 is loaded on the bottom wall 5a of the bottom case 5.Then, as shown in FIGS. 3 and 4, lugs 95a extending from the connectingboard 70 and a lug 95b arranged at the front right corner of the secondshield plate 69 are fitted to respective bosses 46 erected on the bottomwall 5a of the bottom case 5 by means of screws. Note that the lug 95bis secured to the corresponding boss 46 as it is placed on the case 31of the FDD 30, whereas the lugs 95a are respectively secured to thebosses 46 with anchoring members 46b of the HDD 40.

As seen from FIGS. 6 and 9, anchoring members 96a and 96b are formed atthe respective ends of the upright sections 72 and 86 that provide arear wall for the shield frame 62 and the brackets 28 of the hinges 26are respectively secured to the anchoring members 96a and 96b by meansof screws. Thus, the shield frame 62 is designed to support the displayunit 3 too.

As shown in FIGS. 2 and 3, a pair of synthetic resin covers 98a, 98b aresecured to respective rear end areas of the upper surface of the shieldframe 62. These covers 98a, 98b are so designed as to conceal theopenings of the stem bearing portions 10a, 10b from underneath when thetop cover 6 is fitted onto the bottom case 5 and provide bottoms for therespective stem bearing portions 10a, 10b.

As shown in FIG. 3, of the circuit boards 61a through 61e arranged inthree layers, the fourth circuit board 61d located on the top layer isprovided with a spare zone 101 for receiving thereon one or more thanone additional circuit components 100 such as a keyboard controller tobe installed in order to upgrade the portable computer. The spare zone101 is located at the middle of the board unit 60 in the longitudinaldirection of the unit 60 and will be filled with circuit patterns. Thebase plate section 85 of the second shield plate 69 that covers thefourth circuit board 61d from above is provided with a cut out area 102at a position facing at least the spare zone 101 and most of the uppersurface of the fourth circuit board 61d including the spare zone 101 isupwardly exposed through the cut out area 102.

On the other hand, the upper surfaces of the FDD 30, the HDD 40 and thebattery pack 50 are covered by a metal shield plate 105 that alsooperates as a fixture plate. The shield plate 105 comprises, asillustrated in FIGS. 2 through 4 and 12, a flat and rectangular mainsection 105a realized in a form that corresponds to the plan view of thefront half of the bottom case 5. The main section 105a is provided alongits edges with a plurality of lugs 106. The shield plate 105 is thensecured to the lugs 35a, 35b, 36a, 36b, while the lugs 106 are securedby screws 47 to the corresponding bosses 46 on the bottom wall 5a of thebottom case 5. Of the lugs 106, those arranged at the rear corners ofthe main section 105a are laid on the respective lugs 95a, 95b of theshield frame 62 on the bosses 46 so that the shield frame 62 and theshield plate 105 are electrically connected with each other.

Thus, once the lugs 106 of the shield plate 105 are secured to thebosses 46 by screws, the FDD 30, the HDD 40 and the battery pack 50 areclamped by the shield plate 105 and the bottom wall 5a and consequentlyfirmly fixed to the bottom case 5.

As shown in FIG. 4, the main section 105a of the shield plate 105 islocated below the keyboard unit 13, and the reinforcement plate 17 ofthe keyboard unit 13 is located opposing to the shield plate 105 with anarrow clearance therebetween. A pair of metal plate springs 107a and107b are arranged near the respective side edges and on the uppersurface of the shield plate 105. Each of the plate springs 107, 107b areequipped with a plurality of resiliently deformable contact pieces 108,which are held in contact with the reinforcement plate 17 of thekeyboard unit 13 so that the shield plate 105 and the reinforcementplate 17 are electrically connected with each other.

As illustrated in FIG. 12, the shield plate 105 has as integral partthereof an extension 110 extending from the rear end of the main section105a toward the board unit 60. The extension 110 has a shapecorresponding to that of the cut out area 102 and covers the cut outarea 102 and the fourth circuit board 61d that carries thereon the sparezone 101. The extension 110 has at its front end a connecting portion111 as integral part thereof, and the connecting portion 111 is securedto the rear end of the shield frame 62 by means of screws. Thus, theextension 110 may not lift unintentionally, and the board unit 60 isheld between the extension 110 and the bottom wall 5a of the bottom case5.

As seen from FIGS. 4 and 12, the extension 110 is located close to therear half of the top wall 6a of the top cover 6 and has a transverselyextending recess 112 for receiving a reflection type liquid crystaldisplay 113, which is designed to display various operating conditionsof the computer 1o The liquid crystal display 113 has an oblongrectangular plan view while it is held immovable relative to the recess112 in the transverse direction of the housing 4, its position isadjustable forwardly or rearwardly within a given limit.

More specifically, the recess 112 has a width slightly greater than thatof the liquid crystal display, and oppositely arranged pairs of engagingmembers 114a, 114b and 115a, 115b are projecting toward thecorresponding ones from the front and rear edges of the recess. As shownin FIG. 13 in enlarged dimensions, the front and rear sides of theliquid crystal display 113 are separated from the respective engagingmembers 114a, 114b and 115a, 115b by narrow clearances 116 so that theliquid crystal display 113 may be shifted forwardly or backwardly withinthe limit. The top surface of the liquid crystal display 113 is foundabove the upper surface of the extension 110,

An oblong display window 117 is formed through the rear half of the topwall 6a of the top cover 6 to expose the liquid crystal display 113. Atransparent protective cover 118 is fitted to the display window 117.The top wall 6a has as integral part thereof on its inner surface withdownwardly projecting ridges 120a and 120b extending respectively alongthe front and rear edges of the display window 117. As shown in FIG. 13,the ridges 120a and 120b are respectively located right above the upperfront edge and the upper rear edge of the liquid crystal display 113 andoppositely chamfered to produce guide bevels 121a and 121b that providea greater distance therebetween toward the ridgelines.

The guide bevels 121a and 121b are so arranged that they respectivelyabut the upper front edge and the upper rear edge of the liquid crystaldisplay 113 when the top cover 6 is properly put on the bottom case 5.As a result of the abutment, the liquid crystal display 113 is movedforward or rearward as a function of the inclination of the guide bevels121a and 121b to offset any clearances between the display window 117 ofthe top cover 6 and the liquid crystal display 113. At the same time,the liquid crystal display 113 is pressed against the bottom of therecess 112 so that the display 113 may not be allowed to accidentallytilt in any directions.

As illustrated in FIG. 14, the board unit 60 is provided at its rightside with first and second card slots (card storage spaces) 125 and 126for receiving function expansion cards. The card slots 125 and 126 arearranged on a one above the other basis. The lower first card slot 125is formed between the extension 71a of the first shield plate 68 and thepartition 81 of the cover 80 to dimensions typically capable of storingany card conforming to the applicable PCMICA standard including thosefor thick type cards that may have a maximum thickness of 18.0 mm. Thisfirst card slot 125 is designed to typically receive a card, such as anexpansion card 127, which may be constantly used and is held in the slotwithout being frequently drawn out the slot. As may be understood fromFIGS. 9 and 14, the second circuit board 61b is located near an end ofthe first card slot 125 and a connector 300 conforming to the PCMCIAstandard is arranged on the second circuit board 61b. The connector 300is designed to be connected to a terminal section 127a of the expansioncard 127, whereas the terminals of the connector 300 are connected tothe circuit pattern formed on the circuit board 61b.

On the other hand, the second card slot 126 is formed between thepartition 81 of the cover 80 and the base plate section 85 of the secondshield plate 69 and extension 110 of the shield plate 105 disposedadjacent to the base plate section 85. The second card slot 126 isformed to dimensions appropriate to receive a card of type 1 with athickness of 3.3 mm or of type 2 with a thickness of 5.0 mm, e.g., aninterface card 128, which may be frequently inserted and drawn out thecard slot 126. As shown in FIG. 3, the interface card 128 normally hasterminal sections 129a and 129b arranged at opposite ends thereof and athickness smaller than that of the expansion card 127. As may be seenfrom FIG. 3, the fifth circuit board 61e is located close to an end ofthe second card slot 126, and a connector 302 conforming to theapplicable PCMCIA standard is arranged on the fifth circuit board 61e.The connector 302 is designed to be connected to the terminal section129a of the interface card 128, whereas the terminals of the connector302 are connected to the circuit pattern formed on the circuit board61e.

As shown in FIG. 10, side walls of the cover 80 defining the first cardslot 125 have respective outwardly projecting lower end portions thatdefine a pair of guide grooves 303 for guiding the side edges of thecard 127. Each of the lower end portions of the cover 80 is providedwith a pair of projections 304 formed by pressing parts of the lower endportions. These projections 304 project into the respective guidegrooves 303 and abut the respective side edges of the card inserted intothe first card slot 125 to hold the card in position. A total of fourprojections 306 are formed on the extension 71a of the first shieldplate 68 in a manner as described above with regard to the projections304. The projections 306 are designed to abut the lower surface of thecard inserted into the first card slot 125 to hold the card in position,

The partition 81 of the cover 80 that defines the second card slot 126is provided with four projections 308 that are designed to abut thelower surface of the card inserted into the second card slot 126 to holdthe card in position. Additionally, a pair of guides (not shown) arearranged in the second card slot 126 to guide the side edges of thecard.

The first card slot 125 and the second card slot 126 have identicalwidths. In other words, the distance between the guide grooves 303 forthe first card slot 125 and the distance between the guides for thesecond card slot 126 are equal to each other. The card slots 125 and 126differs from each other only in terms of height. FIG. 15 illustratescards conforming to the PCMCIA standard and usable in either the firstcard slot 125 or the second card slot 126. More specifically, a thicktype card 127 as illustrated in FIGS. 10 and 15 is substantiallyrectangularly parallelepipedic and provided with guide ribs 310projecting from lower portions of the respective side walls. The card127 has a thickness DT of 18.0 mm and each of the guide ribs has athickness D1 of 3.3 mm, whereas the lower ends of the guide ribs arespaced from the bottom of the card by a distance Y of 0.85 mm, and thecard has an overall width W1 of 54.0 mm including the guide ribs and hasa width W2 of 51.0 mm without the guide ribs.

The type 3 card has a thickness D3 of 10.5 mm which is smaller than thethickness of the thick type card but is identical with the thick typecard 127 in any other dimensions. The type 2 card has a thickness D2 of5.0 mm and a width W2 of 48.0 mm but is identical with the thick typecard 127 in any other respects. Finally, the type 1 card has a thicknessD1 of 3.3 mm and a distance Y of 0 mm between the lower ends of theguide ribs and the bottom of the card but identical with the cards ofthe type 2 in any other respects.

Regardless of the type, each card is provided with a terminal section(127a, 129a or 129b) conforming to the PCMCIA standard, which is to beconnected to the connector 300 or 302 arranged in the card slot 125 or126.

As described above, the guide ribs 310 of the cards of any type havecommon dimensions, and each card is inserted into the first or secondcard slot 125 or 126 while the guide ribs 310 are guided by the guidegrooves 303 or the guides of the card slots. Thus, the first card slot125 can selectively receive any one of the cards of any types, whereasthe second card slot 126 can electively stores one of cards of type 1and type 2 which are normally designed to be frequently loaded andunloaded.

FIG. 16 illustrates the control system for controlling the cards loadedin the first and second card slots 125 and 126. The card loaded in theyfirst card slot 125, typically an I/O card 127, is connected to a cardcontroller 323 via the connector 300. The card loaded in the second cardslot 125, typically an interface card 128, is connected to the cardcontroller 323 via the connector 302. The card controller 323 iscontrolled by a socket service 324 and a card service 325 of a BIOS-ROM.

The card controller 323 is then connected to the internal bus of thecomputer to specify an address space to be used to access the cards 127and 128, control read/write operations and detect card insertions andejections. The socket service 324 basically has basic function requiredto control hardware and is capable of coordinating the cards 125 and126, the card controller 323 and other pieces of hardware of differentfunctional levels. The card service 325 defines the application softwareinterface required to access the cards 125 and 126 from a givenapplication program by using OS (operating system) 326.

As described above, the computer is equipped with the first card slot125 capable of storing the thick type card, and the second card slot 126for receiving a thin card of type 1 or type 2. Thus, the computer can beoperated while two cards are simultaneously stored in the first andsecond card slots 125 and 125, for example, while the first card slotstores a selected type of card, e.g., an I/O card and the second cardslot stores a card such as a security card which is frequently insertedand ejected from the slot. As a result, the computer has a highexpansion capability.

As shown in FIGS. 14 and 17, the housing 4 has in its rear half anopening 135 that communicates with the first and second card slots 125and 126. The opening 135 specifically comprises a side opening 135aformed through the right side wall of the housing 4, a top opening 135barranged through the top wall 6a of the top cover 6 and extending fromthe side opening 135a, and a bottom opening 135c cut through the bottomwall 5a of the bottom case 5 and also extending from the side opening135a. A flat receiving portion 136 is horizontally extending from andlocated adjacent to the edge of the top wall 6a that defines an end ofthe top opening 135b.

As illustrated in FIGS. 14, 17 and 18, a cover 140 is fitted to thehousing 4 to cover the opening 135. The cover 140 comprises a coversupport 141 to be rigidly fitted to the bottom case 5 of the housing 4,a first cover member 142 removably fitted to the cover support 141, anda second cover member 143 fitted to the cover support 141 and rotatablebetween an opened position and a closed position.

The cover support 141 includes a flat fitting portion 144 to be receivedin the bottom opening 135c, and a pair of vertical support walls 145a,145b extending from the fitting portion 144 and fitted into the sideopening 135a. The support walls 145a, 145b are separated from each otherin the depth direction of the housing 4 and located in the side opening135a. These support walls 145a, 145 are rigidly fitted to respectivebosses 146a, 146b of the bottom case 5 by means of screws 147 and have aheight substantially equal to that of the side wall 5b of the bottomcase 5. Additionally, the support walls 145a, 145b are respectivelyprovided with engaging holes 148a, 148b and pivots 149a, 149b.

The first cover member 142 is used to selectively conceal and expose thefirst card slot 125 and is formed as an oblong flat plate extendingbetween the support walls 145a and 145b. The first cover member 142 isdesigned to conceal the lower half of the side opening 135a and providedwith a pair of engaging projections 150a, 150b at locations facing thesupport walls 145a, 145b. The first cover member 142 is fitted to thecover support 141 to cover the first card slot 125 from the outside whenthe engaging projections 150a, 150b are releasably engaged withrespective engaging holes 148a, 148b formed in the support walls 145a,15b. Under this condition, the outer surface of the first cover member142 is flush with that of the side wall 5b of the bottom case 5 andconstitutes part of the side wall 5b.

The second cover member 143 is designed to selectively conceal thesecond card slot 126 and comprises a top wall section 152 for closingthe top opening 135b and a side wall section 153 extending from the topwall section 152 to close the upper half of the side opening 135a. Boththe top wall section 152 and the side wall section 153 have a flat andoblong form extending in the depth direction of the housing 4. The sidewall section 153 is provided with a pair of legs 154a, 154b downwardlyextending from its front and rear ends respectively. The legs 154a, 154bare used to hold the vertical walls 145a, 145b of the cover support 141from the front side and the rear side respectively. The legs 154a, 154bare provided with respective bores 155a, 155b for rotatably receivingthe respective pivots 149a, 149b. Once the pivots 149a, 149b are set inthe respective bores 155a, 155b, the second cover member 143 becomesrotatable around the pivots 149a, 149b between a closed position whereit conceals the top opening 135b and the upper half of the side opening135a and an opened position where it gets to expose the openings 135band 135a as it is rotated counterclockwise.

When the second cover member 143 is rotated in its closed position, theupper surface of the top wall section 152 is coplanar with the uppersurface of the top wall 6a of the top cover 6 and, at the same time, theouter surface of the side wall section 153 is also coplanar with theouter surface of the side wall 6b of the top cover 6 to appear as if anintegral part of the top cover 6. Under this condition, the top wallsection 152 is located on the receiving portion 136 within the topopening 135b to suppress any upward displacement of the top cover 6.

When the second cover member 143 is rotated to its closed position,anchoring projections 156, 156 arranged along the front edge of the topwall section 152 are engaged with respective hooks 157a, 157b projectingfrom the corresponding edge of the top wall 6a to hold the second covermember 143 in the closed position as may be seen from FIG. 14.

As illustrated in FIGS. 14, 17 and 18, the side wall section 153 of thesecond cover member 143 is provided with a terminal access opening 160leading to the second card slot 126. The terminal access opening 160extends in the depth direction of the housing 4 and is opposite to theterminal section 129b of the interface card 128 in the second card slot126.

A lid plate 161 for opening and closing the terminal access opening 160is fitted to the side wall section 153. It is made of a plate, having anoblong front view corresponding to that of the terminal access opening160, and provided with a pair of pivots 162 and a pair of anchoringprojections 163 arranged lengthwise near the respective side ends (onlyone of the pivots and one of the anchoring projections are shown in FIG.14). The pivots 162 are rotatably held at the respective edges of theside wall section 153 defining the terminal access opening 160 so thatthe lid plate 161 may be rotatable around the pivots 162 between aclosed position where it covers the terminal access opening 160 and anopened position where it gets to expose the terminal access opening 160as it is rotated counterclockwise when the lid plate 161 is placed inits closed position, the anchoring projections 163 are engaged with theedge of the side wall section 153 defining the terminal access opening160 to hold the lid plate 161 in the closed position. Under the closedcondition, the outer surface of the lid plate 161 is coplanar with theouter surface of the side wall section 153 of the cover member 142,thereby constituting part of the side wall section 153.

With the cover 140 having a configuration as described above, when thelid plate 161 is opened while the interface card 128 is loaded in thesecond card slot 126 as illustrated in FIG. 14, the terminal section129b of the interface card 128 is exposed to the outside through theterminal access opening 160 so that the connector of an externalexpansion device may be connected to the terminal section 129b withoutopening the second cover member 143.

As illustrated in FIGS. 5, 19 and 20, the board unit 60 is provided atits left end with a third card slot 131 disposed between the fifthcircuit board 61e and the base plate section 85 of the second shieldplate 69. This third card slot 131 is provided with a card insertionport 133 cut through the left side wall of the shield frame 62. Thethird card slot 131 is designed to receive another expansion card 132through the card insertion port 133. A connector (not shown) to beconnected to the card 132 is arranged on the fifth circuit board 61e.

As shown in FIGS. 5, 19 and 20, a card inserting slot 170 is cut throughthe rear half of the left side wall of the housing 4, leading to thethird card slot 131. More specifically, the card inserting slot 170 isformed in the side wall 6b of the top cover 6 and extends in the depthdirection of the housing 4.

The side wall 6b of the top cover 6 is provided with a lid plate 171 forclosing and opening the card inserting slot 170. The lid plate 171 hasan oblong front view conforming to that of the card inserting slot 170and is provided at its front and rear ends with a pair of pivots 172 anda pair of anchoring projections 173 (only one of the pivots and one ofthe projections are shown in FIGS. 19 and 20). The pivots 172 arerotatably held at the respective edges of the side wall 6b defining thecard inserting slot 170 so that the lid plate 171 is rotatable aroundthe pivots 172 between a closed position where it covers the cardinserting slot 170 and an opened position where it gets to open the cardinserting slot 170 as it is rotated lift side.

When the lid plate 171 is placed in its closed position, the anchoringprojections 173 are engaged with the respective edges of the side wall6b defining the card inserting slot 170 to hold the lid plate 171 to theclosed position. Under the closed condition, the outer surface of thelid plate 171 is coplanar with the outer surface of the side wall 6b ofthe top cover 6 and constitutes part of the side wall 6b.

As illustrated in FIGS. 5, 19 and 20, the board unit 60 is provided witha power switch 180 at its left side end. The power switch 180 comprisesa depressible actuator 181 projecting through the left side wall of theshield frame 62, or the upright section 72 of the first shield plate 68,toward the side wall 5b of the bottom case 5.

A synthetic resin control button 182 to be used for turning on and offthe power switch 180 is arranged on the side wall 5b of the bottom case5. As illustrated in FIGS. 21 and 22, the control button 182 has arectangular push pad 183 to be depressed by a finger tip of theoperator. The pad 183 is exposed from the left side of the bottom case 5through a hole 184 cut through the side wall 5b. A pair of stopper walls185a, 185b are arranged to the opposite lateral sides of the pad 183 sothat, once the pad is set in position, they project toward the uprightsection 72 of the first shield plate 68. The stopper walls 185a, 185bare provided as integral part thereof with respective support members186a, 186b extending downward. The lower ends of the support members186a, 186b are mutually connected by a flat and oblong coupling portion187. The support members 186a, 186b and the coupling portion 187 areresiliently deformable. The coupling portion 187 is located below thepad 183 and placed on the bottom wall 5a of the bottom case 5.

A pair of support walls 189a, 189b are formed on the bottom wall 5a ofthe bottom case 5 and located under the hole 184. The support walls189a, 189b are provided on the upper edges with grooves 190, 190 intowhich the coupling portion of the control button 182 is fitted. Thus,the control button 182 is held on the bottom wall 5a of the bottom case5 by way of the coupling portion 187 so that the pad 183 is held in thehole 184 and in parallel to the side wall 5b by means of the resilientforce of the coupling portion 183 and the support members 186a, 186b.

When the push pad 183 is depressed with a finger tip as shown in FIG.20, the coupling portion 187 is deformed along with the support members186a, 187 until the pad 183 is pushed into the bottom case 5 and thestopper walls 185a, 185b abut the upright section 72. The stroke ofmovement of the pad 183 is defined by the stopper walls 185a, 185b.

The push pad 183 has on its lower end of the back side a pusher lug 191extending upward as integral part thereof. The pusher lug 191 isresiliently deformable to move toward and away from the pad 183, and itsfree upper end is held in contact with the actuator 181. Thus, as thepad 183 of the control button 182 is depressed with a finger tip, theactuator 181 is pushed back by the pusher lug 191 to turn on or off thepower switch 180.

With the power switch 180 configured as described above, the push pad183 can be depressed until the stopper walls 185a, 185b abut the shieldframe 62. Since the resiliently deformable pusher lug 191 is disposedbetween the pad 183 and the actuator 181, even when the stroke of thepad 183 is increased due to deformation of the stopper walls 185a, 185band the like, any excessive stroke of the pad 183 can be absorbed by theelastic deformation of the pusher lug 191. Thus, as the push button 182is pushed, the actuator 181 can be prevented from being subjected toexcessive load, thereby preventing damage or other trouble with thepower switch 180.

As illustrated in FIGS. 7 and 23, the bottom case 5 contains in the leftend of the front half a lock mechanism 200 for manually releasablylocking a battery pack 50 in the battery storage section 53. The lockmechanism 200 comprises a lock lever 201 for releasably engaging thecase 51 of the battery pack 50. The lock lever 201 is located betweenthe left side portion of the peripheral wall 5b of the bottom case 5 andthe left side guide wall 52a. The lock lever 201 comprises, asillustrated in FIG. 27, a cylindrical boss 202, an engaging arm 203extending from the outer periphery of the boss 202, and an pressing arm204 also extending from the outer periphery of the boss 202 in adirection opposite to that of the engaging arm 203. The boss 202 isrotatably supported by a pivot 205 standing on the bottom wall 5b of thebottom case 5 so that the engaging arm 203 and the pressing arm 204 arerotatable around the pivot 205.

The left side guide wall 52a has, as illustrated in FIG. 7, a notchedportion 207 opening to the battery storage section 53. The notchedportion 207 is located to oppose the engaging arm 201 of the lock lever201 so that the engaging arm 203 and the corresponding side of the case51 come to face each other through the notched portion 207.Additionally, the case 51 of the battery pack 50 is provided on its sidewall with an engaging recess 208 which faces the notched portion 207when the battery pack 50 is properly loaded into the battery storagesection 53. Then, the engaging recess 208 is located opposite to anengaging tip 209 formed on the free end of the engaging arm 203.

As seen from FIGS. 23, 24A and 24B, a torsion coil spring 210 as a firstspring is arranged behind the lock lever 201. The torsion coil spring210 comprises a coiled section 210a supported on a support pillar 211standing on the bottom wall 5a, and a pair of arms 210b, 210c extendingfrom the coil section 210a. The free end of the arm 210b is anchored tothe bottom case 5 whereas the free end of the arm 210c is hooked on theengaging arm 203. Thus, the lock lever 201 is urged by the spring 210 torotate clockwise so that engaging tip 207 of the engaging arm 203 facesthe notched portion 207 and projects into the battery storage section53.

Thus, when the battery pack 50 is completely pushed into the batterystorage section 53, the engaging tip 207 comes to engage with theengaging recess 208, thereby locking the battery pack 50 in the batterystorage section 53.

The bottom case 5 is provided on the left side portion of the peripheralwall with a window 213 through which a finger tip may go through uponreleasing the lock. The window 213 is located to face the pressing arm204 of the lock lever 201. As shown in FIG. 24B, when the pressing arm204 is pushed by a finger tip inserted through the window 213, the locklever 201 is rotated counterclockwise against the urging force of thetorsion coil spring 210. As the lock lever 201 is rotatedcounterclockwise, the engaging tip 209 is disengaged from the engagingrecess 208 to release the battery pack 50 out of the locked condition.

The lock mechanism 200 additionally comprises a shutter 215 forselectively closing and opening the window 213. The shutter 215 islocated in front of the lock lever 201 and between the left side guidewall 52a and the peripheral wall 5b of the bottom case 5. As illustratedin FIGS. 26 and 27, the shutter 215 comprises a side wall section 216extending along the inner surface of the peripheral wall 5b of thebottom case 5, a top wall section 217 extending horizontally from theupper end of the side wall section 216 toward the guide wall 52a, and afront wall section 218 connecting the front end of the top wall section217 and that of the side wall section 216.

As shown in FIG. 26, the lower end of the side wall section 216 isslidably fitted in a guide groove 220 formed on the bottom wall 5a ofthe bottom case 5 and extending in the depth direction of the housing 4.The top wall section 217 and the front wall section 218 are slidably incontact with the guide wall 52a. Thus, while being guided by the guidewall 52a and the guide groove 220, the shutter 215 is slidable between aclosed position where it is located between the window and the pressingarm 204 of the lock lever 201 to close the window and an opened positionwhere it opens the window 213 to expose the pressing arm 204 of the locklever 201. There is provided a compression coil spring 222 under acompressed condition between the front wall section 218 of the shutter215 and a spring holder 221 disposed at the front end of the bottom case5 so that the shutter 215 is constantly urged toward its closed positionwhere it closes the window 213.

When the shutter 215 is in its closed position, the pressing arm 204 ofthe lock lever 201 is found inside the side wall section 216 of theshutter 215 and constantly pressed against the inner surface of the sidewall section 216, as illustrated in FIG. 23. When the shutter is movedto its opened position as illustrated in FIG. 24A, the side wall section216 of the shutter 215 leaves the pressing arm 204 to make the latterexposed to the outside through the window 213. At the same time, thelock lever 201 is rotated clockwise by an angle corresponding to thethickness of the side wall section 216 as it is urged to rotate by thetorsion coil spring 210. Consequently, the front end of the pressing arm204 comes to face the front edge 216a of the side wall section 216. Ifthe shutter 215 is released from the finger tip that holds it, the frontend of the pressing arm 204 is hooked by the front end of the pressingarm 204 as the shutter moves toward the closed position by the urgingforce of the compression coil spring 222, so that the shutter 215 isheld to its opened position against the urging force of the compressioncoil spring 222.

The side wall section 216 is provided with a finger tip receiving rib223 facing the window 213.

As illustrated in FIGS. 1, 18 and 28, the bottom case 5 is equipped onits right side of the front half with an expansion connector 231 towhich a track ball 230 is to be connected. A track ball 230 is one ofthe pointing devices used for specifying a particular position on thescreen of the liquid crystal display 21 and, as shown in FIG. 32,provided with a spherical control section 233 on the upper surface ofits main body case 232. An operator can shift the cursor position in thedisplay screen and perform other operations by appropriately rotatingthe control section 233 with a finger tip. The main body case 232 isprovided at its one end with a connector 235 that may be removablyfitted to the expansion connector 231. The connector 235 comprises asynthetic resin connector body 236 having a pair of engaging projections236a, 236b and a pair of contact terminals 237,237 arranged between theengaging projections 236a, 236b.

As illustrated in FIG. 28, the expansion connector 231 of the bottomcase 5 is provided with a synthetic resin connector body 240. Theconnector body 240 is formed of an elongated box extending lengthwise inthe bottom case 5, and is integrally provided with a pair of flanges241a, 241b extending from the opposite longitudinal ends. The connectorbody 240 is arranged along the right side portion of the peripheral wall5b of the bottom case 5 with the flanges 241a, 241b rigidly secured to apair of respective bosses 242a, 242b projecting upward from the bottomwall 5a by means of screws 243. As shown in FIG. 31, the connector body240 is located to the right of the FDD 30.

As shown in FIG. 29, the connector body 240 is also provided with a pairof engaging recesses 244 to which the engaging projections 36a, 36b ofthe connector 235 are removably fitted. The recesses 244 are arrangedopposing the right side portion of the peripheral wall 5b of the bottomcase 5. A pair of terminal plates 245 are arranged between the engagingrecess 244 to establish electric connection with the respective contactterminals 237, 237. The terminal plates 245 are electrically connectedto the board unit 60 through a flexible connecting board 246. Theengaging recesses 244 and the connector plates 245 of the connector body240 are exposed to the outside through an elongated connector accessopening 248 formed in the peripheral wall 5b of the bottom case 5.

The connector body 240 is molded with a metal conductor plate 250 asintegral part thereof. The conductor plate 250 has a first exposed area251 connecting the tops and the bottoms of the engaging recesses 244 anda pair of second exposed areas 252 extending from the first exposed area251 and arranged on the rear surface of the connector body 240. As shownin FIG. 29, the first exposed area 251 extends closer to the outerextremities of the engaging recesses 244 than the terminal plates 245and also to above and below the terminal plates 245, 245.

As illustrated in FIG. 28, the second exposed areas 252 are providedwith respective grounding terminals 255a 255b. In this embodiment, oneof the grounding terminals, or the terminal 255a, is laid under thelower surface of the front flange 241a, whereas the other groundingterminal 255b is laid on the upper surface of the rear flange 241b. Agrounding metal fitting 256 is interposed between the grounding terminal255a and the boss 242a and secured to the boss 242a by means of a screw243. A grounding metal fitting 256 has as an integral part thereof aconductive member 257, which conductive member 257 is secured onto thelug 36b by means of a screw 258 and receives thereon the shield plate105. Thus, conductor plate 250 of the connector body 240 is electricallyconnected to the casing 31 and the shield plate 105 via the groundingterminal 255a and the grounding metal fitting 256.

With such an arrangement, the electrostatic charge that may have beenaccumulated on the contact terminals 237 and/or the terminal plates 245can be discharged therebetween when the connector 235 of the track ball230 is connected to the expansion connector 231. However, since theexpansion connector 231 is molded as an integral part thereof with theconductor plate 250 having the first exposed area 251 extending closerto the outer extremities of the engaging recesses 244 than the terminalplates 245 and also to above and below the terminal plates 245, thefirst exposed area 251 approaches the contact terminals 237 before itapproaches the terminal plates 245 when the two connectors are puttogether so that any accumulated electrostatic charge may be dischargedfirstly between the first exposed area 251 and the contact terminals237. Because the conductor plate 250 is electrically connected to thecasing 31 of the FDD 30 via the grounding metal fitting 256, theelectrostatic charge will be safely led to the casing 31 of the FDD 30and then to the shield plate 105 for discharging.

The bottom case 5 is provided with a shutter plate 260 for selectivelyclosing and opening the connector access opening 248. The shutter plate260 has a rectangular plan view that corresponds to that of theconnector access opening 248 and slidable lengthwise along the rightside portion of the peripheral wall 5b of the bottom case 5 between aclosed position where it covers the connector access opening 248 and anopened position where it exposes the connector access opening 248 andhence the engaging recesses 244 of the connector body 240.

As shown in FIGS. 28 and 31, a guide wall 261 is arranged on the bottomwall 5a of the bottom case 5 to slidably hold the shutter plate 260between the peripheral wall 5b of the bottom case 5 and itself. Theguide wall 261 is located behind the connector body 240 and has a flatwall section 262 extending forward from the front end of the guide wall261 and between the connector body 240 and the peripheral wall 5b. Thewall section 262 is designed to hold the shutter plate 260 between theperipheral wall 5b and itself. Therefore, it may be understood that theexpansion connector 231 operates also as a guide wall for guiding thesliding movement of the shutter plate 260.

The shutter plate 260 is equipped with a rib 263 for receiving a fingertip coming into the connector access opening 248.

Next, there will be described a method of assembling the FDD 30, HDD 40,battery pack 50, and board unit 60 in the bottom case 5 with respect tothe computer 1 having the above-mentioned arrangement.

Firstly, an FDD 30, an HDD 40, a battery pack 50 and a board unit 60 areplaced on the respective proper positions on the bottom wall 5a of thebottom case 5. Then, the lug 95b extending from the connecting board 70of the shield frame 62 is laid on the upper surface of the metal casing31 of the FDD 30 and the slot 94 formed near the left side of theconnecting board 70 is aligned with the leading end of the battery pack50. Now, the board unit 60 is partly superposed on the FDD 30 and thebattery pack 50.

Thereafter, the lug 95a extending from the connecting board 70 of theboard unit 60 is secured to the corresponding boss 46 together with thefixture 45b of the HDD 40 by means of a screw 47 and the other lug 95bis secured to the other boss 46 also by means of a screw 47.

Under this condition, the shield plate 105 is placed on the FDD 30, theHDD 40, the battery pack 50 and the board unit 60. Then, the mainsection 105a of the shield plate 105 is secured to the brackets 34a, 34bof the FDD 30 by means of screws, and the lugs 106 arranged along theedges of the main section 105a are secured to the respective bosses 46also by means of screws. Note that one of the lugs 106 is placed on thefixture 45a and then secured to the corresponding boss 46 together withthe fixture 45a, as shown in FIG. 4.

At the same time, the connector member 111 of the extension 110 of theshield plate 105 is secured to the rear end of the shield frame 62 bymeans of screws so that the extension 110 may not lift unintentionally.When the shield plate 105 is secured to the bosses 46 by means ofscrews, the FDD 30, the HDD 40, the battery pack 50 and the board unit60 are held between the shield plate 105 and the bottom wall 5a of thebottom case 5, so that these functional components are rigidly securedto their proper positions on the bottom wall 5a.

As described above, according to the embodiment of the presentinvention, the FDD 30, the HDD 40, the battery pack 50 and the boardunit 60 of the above embodiment are securely held between the shieldplate 105 and the bottom wall 5a by simply securing the shield plate 105that carries thereon these functional components to the bosses 46 bymeans of screws. Thus, a plurality of functional components can bealigned and secured in a very simplified manner.

Accordingly, the assembling of the computer 1 can be easily carried outwithout requiring the functional components 30, 40, 50 and 60 to beindividually and sequentially secured by means of screws in a lengthymanner as in the case of conventional portable computers.

Besides, it is not necessary to provide many bosses on the bottom wall5a at positions individually corresponding to the functional components30, 40, 50 and 60. Thus, the total number of bosses to be formed on thebottom wall 5a can be reduced, so that the bottom wall 5a of the bottomcase 5 can be formed in a simple shape without concave or convexportions. In accordance with the reduction of the number of bosses, thebottom case 5 may show a simple structure and those spaces which aredefined for arranging conventional bosses can be used as spaces forreceiving components.

Because more space is made available within the bottom case 5, thefunctional components 30, 40, 50 and 60 may be placed very close to thebottom wall 5a and any adjacent ones of the functional components 30,40, 50 and 60 may be brought closer to each other on the bottom wall 5ato reduce the overall space required for the components.

With the computer 1 having the configuration as described above, sincethe lugs 95b of the board unit 60 to be secured to the bosses 46 arepartly placed on the casing 31 of the FDD 30, the FDD 30 may be pressedagainst the bottom wall 5a by way of the lugs 95b. In other words, theadjacently arranged board unit 60 and the FDD 30 can be securely fittedto the bottom wall 5a by a single operation of driving screws 47 intothe bottom wall 5a, thereby reducing the total number of portions to bescrewed and simplifying the assembling operation.

Additionally, since the fixture 45b of the HDD 40 and the lugs 95a ofthe board unit 60, and the fixture 45a of the HDD 40 and the lug 106 ofthe shield plate 105 are commonly secured to the respective bosses 46,the total number of screws 47 and bosses 46 can be further reduced,thereby simplifying the assembling operation and increasing the mountingspace in the bottom case 5.

Furthermore, since the shield plate 105 is used as the fixture plate forholding the functional components 30, 40, 50 and 60 between itself andthe bottom wall 5a, any high frequency noises generated by thefunctional components 30, 40, 50 and/or 60 during operation can beshielded within the housing 4. Thus, interference of radio andtelecommunications due to leakage of the high frequency noises can beprevented.

Moreover, the FDD 30, the battery pack 50 and the board unit 60 can bereleased from the bottom case 5 by simply undoing the screws fasteningthe shield plate 105 to the bottom case 5 and separating the shieldplate from the bottom case. The HDD 40 can also be released from thebottom case 5 by removing the shield plate 105 from the bottom case 5and undoing a single screw fastening the fixture 45a to the bottom case5. Thus, all the functional components 30, 40, 50 and 60 that comprisemetal parts, the metal shield plate 105 and the synthetic resin bottomcase 5 may be easily separated from one another.

This means that, when the computer 1 loses its service life, partsformed of synthetic resin and metal parts can be easily separated fromeach other, so that any parts can be easily recycled and can improve theproblem of environmental pollution.

As described earlier, the board unit 60 of the above embodiment isrealized by arranging first through third circuit boards 61a through 61con a first shield plate 68 in two layers, while securing fourth andfifth circuit board 61d and 61e side by side onto a second shield plate69, and then superposing the first and second shield plates 68, 69 witheach other, so that the circuit boards 61a through 61e may be arrangedin three layers. So the five circuit boards 61a through 61e connectedone another through the flexible connecting boards 65a to 65d are keptin a multilayered manner before they are assembled in the bottom case 5.

Further, the circuit boards 61a to 61d are arranged in layers and arecompletely surrounded by the shield plates 68 and 69, and a single boardunit 60 having a shielding effect is constructed by the circuit boardsand the shield plate. Thus, the housing 4 does not need to have aconductive layer for shielding noises.

Since both the first shield plate 68 and the second shield plate 69 aremade of a metal plate, they are by far stronger than a conductive layerprepared by plating and, therefore, least liable to be damaged when theboard unit 60 is mounted on the housing 4. Consequently, high frequencynoises that may be generated from any of the circuit components 66 areeffectively confined within the housing 4 to thereby improve thereliability of the computer. Additionally, since the housing 4 isprovided on its inner surface with no conductive layer, the operation ofmounting the circuit boards 61a to 61e can be carried out without payingparticular attention to avoiding a collision between the circuit boardsand the housing 4 which may adversely affect the efficiency of themounting operation.

With the above-mentioned arrangement, since the circuit boards 61a to61e form a unit with the first and second shield plates 68 and 69 andare then mounted on the housing 4, the bottom case 5 only requiresbosses arranged on the bottom wall 5a for securing the first shieldplate 68. Thus, the housing 4 does not need to have many fixing portionsto which the circuit boards are individually secured, so that the insideof the housing 4 may have a very simplified profile.

Further, the circuit boards 61a to 61e are rigidly held by the shieldplates 68 and 69 within the housing 4 without the fear of being shaken,and it is possible to easily carry out the operation of mounting circuitboards 61a to 61e within a limited space inside the housing 4.

To upgrade the computer 1 having a configuration as described above byinstalling in the spare zone 101 of the board unit 60 an additionalcircuit component 100 such as a keyboard controller, the display unit 3is firstly rotated to the third position, where the display unit 3 isaway from the top cover 6. Under this condition, the top cover 6 and thekeyboard unit 13 are removed from the bottom case 5 to expose the uppersurface of the bottom case 5.

Now, the shield plate 105 covering the FDD 30, the HDD 40 and thebattery pack 50 and the board unit 60 come to be exposed. Then, theshield plate 105 is taken out by undoing the screws 47 securely holdingthe shield plate 105 to the bottom case 5. Since the shield frame 62 ofthe board unit 60 arranged adjacent to the shield plate 105 has a cutout area 102 for exposing the spare zone 101, and the shield plate 105has as an integral part thereof an extension 110 for concealing thespare zone 101, the spare zone 101 on the fourth circuit board 61d comesto be exposed as the shield plate 105 is moved away.

Therefore, without removing the board unit 60 from the bottom case 5 orexploding the board unit 60, a circuit components 100 may be installedinto the spare zone 101 and the components currently installed in thespare zone 101 may be replaced by an upgraded circuit component 100.Thus, any operation of adding and/or replacing circuit component 100 canbe carried out easily despite the fact that the circuit boards 61a to61e are arranged in three layers.

In the above-mentioned embodiment, the circuit components 66 on thecircuit boards 61a to 61d arranged in three layers generate heat toraise the temperature of the board unit 60. Since the third circuitboard 61c disposed in the middle of the layers of the circuit boards 61ato 61d is dedicated to power supply, it generates heat at a considerablerate and the generated heat may be stored around it to thereby locallyraise the temperature of a particular area of the board unit 60.

However, because of the fact that the shield plate 105 having a surfacearea substantially equal to the entire surface area of the rear half ofthe bottom case 5 is held in contact with the shield frame 62 of theboard unit 60 and that the shield frame 105 is provided with anextension 110 that directly covers the fourth circuit board 61d, theheat generated in the board unit 60 is efficiently transmitted to thelarge shield plate 105. Moreover, since the shield plate 105 is held incontact with the reinforcement plate 17 that covers the entire surfacearea of the underside of the keyboard unit 13 by way of the platesprings 107a and 107b, the heat transmitted to the shield plate 105 isfurther sent to the reinforcement plate 17, where it is radiated intothe atmosphere.

Therefore, any heat in the board unit 60 can be effectively andefficiently transmitted to the shield plate 105 and then radiatedtherefrom so that the board unit 60 is protected against the danger ofstoring heat in a particular area thereof. Thus, although the housing 4of the computer 1 is made of a synthetic resin material that poorlytransmits heat, the board unit 60 that generates heat at an enhancedrate can be reliably cooled without requiring a particularly designedcooling mechanism such as a fan.

Since a dedicated cooling mechanism is not required for the computer 1,the number of the components can be reduced and its components can bearranged within the housing 4 without the risk of overloading. Further,a problem of noise generated can be omitted.

With the computer 1, a battery pack 50 is loaded into the batterystorage section 53 through the battery pack insertion opening 54 formedon the front side of the bottom case 5. As a lateral side of the case 51of the battery pack 50 reaches the notched portion 207, the engaging tip209 of the lock lever 201 gets in touch with the side of the cassette51. Thus, the lock lever 201 is rotated counterclockwise to allow theinsertion of the battery pack 50 when the battery pack 50 is insertedinto the storage section 53 until the battery pack 50 abuts the stoppers56a, 56b, the engaging recess 208 of the case 51 faces the engaging tip209 of the lock lever 201 and the engaging tip 209 comes to be engagedwith the engaging recess 208 under the urging force of the torsion coilspring 210.

Then, the battery pack 50 is locked in the battery storage area 53 tobecome unretrievable from the area.

To unlock the battery pack 50, it is necessary to insert a finger tipinto the housing 4 through the window 213 and hold the rib 223 of theshutter 215 and then slidingly move the shutter 215 to its open positionagainst the urging force of the compression coil spring 222. Then, thelock lever 201 is urged to rotate clockwise by the torsion coil spring210 and, since the front end of the pressing arm 204 of the lock lever201 is held in contact with the inner surface of the side wall section216 of the shutter 215, the inner surface of the side wall section 216leaves the front end of the pressing arm 204 as the shutter 215 is movedto its open position. Then, as the side wall section 216 is moved awayfrom the pressing arm 204, the lock lever 201 is rotated by an anglecorresponding to the thickness of the side wall section 216 and thefront end of the pressing arm 204 comes to face the front edge 216a ofthe side wall section 216. Because the shutter 215 is urged toward itsclosed section by the compression coil spring 222, the front edge 216aof the side wall section 216 of the shutter comes to be engaged with thepressing arm 204 so that the shutter 215 is held to its open positionwhen the shutter 215 is released from the finger tip holding it.

Now, since the window 213 is open and the pressing arm 204 of the locklever 201 is exposed to the outside through the window 213, it can bepushed inward by a finger tip. Then, the lock lever 201 is rotatedcounterclockwise against the urging force of the torsion coil spring 210and the engaging tip 209 of the lock lever 201 is released from theengaging recess 208 of the battery pack 50. So, as long as the pressingarm 204 is pushed inward by a finger tip, the battery pack 50 is held inan unlocked condition and, therefore, it can be pulled out of thebattery storage area 53 by holding the downward ridge 55 arranged at thefront end of the bottom of the battery pack 50 with a finger tip.

When the pressing arm 204 is pushed inward, the front end of thepressing arm 204 is moved away from the front edge 216a of the side wallsection 216 and, therefore, the shutter 215 is released at the sametime. If the finger tip pushing the pressing arm 204 inward is pulledout of the window 213 to release the pressing arm 204, the shutter 215is urged to slidingly come to the closed position by the resilient forceof the compression coil spring 222 to automatically conceal the window213.

With a lock mechanism 200 configured in a way as described above, theshutter 215 is engaged with the pressing arm 204 of the lock lever 201and held to its position even when the shutter 215 is slidingly moved toits open position and, therefore, it is not necessary to somehow holdthe shutter 215 immovable while pushing the pressing arm 204 of the locklever 201 inward. So, the existence of the shutter 215 for concealingthe lock lever 201 does not interfere with the intended easy operationof the lock lever 201.

When the battery pack 50 is unlocked in the storage area 53 as thepressing arm 204 of the lock lever 201 is pushed inward, the engagementof the pressing arm 204 and the side wall section 216 of the shutter isreleased. Thus, if the finger tip is pulled out of the window 213, theshutter is slidingly moved to its closed position to automaticallyconceal the window 213. This is a foolproof system that never allows thewindow to be left open and the lock lever 201 to be falsely operated.

While the front end of the pressing arm 204 of the lock lever 201 isengaged with the front edge 216a of the shutter when the shutter 215 ismoved to its open position in the above embodiment, the shutter 215 andthe lock lever 201 may alternatively be so designed that the front endof the pressing arm 204 abuts the inner surface of the shutter 215 whenthe latter is moved to the open position, as illustrated in FIG. 33.With such an arrangement, since two actions of opening the shutter 215and then pushing the pressing arm 204 of the lock lever 201 inward arerequired for relieving the locked condition of the lock mechanism 200,there will not be any risk of unintentionally undoing the fastened lockmechanism 200 while the computer is being shipped. Once the fastenedcondition of the lock mechanism 200 is relieved, the lock lever 201 isturned back to its locked position by simply releasing the finger tipthat holds the pressing arm 204 and the shutter 215 and the shutter 215is automatically moved back to the closed position by the resilientforce of the spring 222. This is also a foolproof system that neverallows the window 213 to be unintentionally left open and the lock lever201 to be falsely operated.

It may be needless to say that the present invention is not limited tothe above embodiment and various modifications may be made withoutdeparting the spirit and the scope of the invention.

For instance, while the shield plate of the above embodiment covers onlyfunctional components such as an FDD and an HDD, it may alternatively beintegrally formed with a wall section extending downward from theperipheral edge of the shield plate to conceal the functional componentsfrom above and laterally.

Similarly, while the shield plate operates also as a fixture plate, anindependent fixture plate may alternatively prepared. Such anindependent fixture plate may be made of a synthetic resin material.

Components to be stored within the housing are not limited to thosedescribed above by referring to the embodiment such as a battery packand may include expansion device such as a modem unit and hard discdrives.

While the circuit boards are arranged in three layers in the aboveembodiment, the number of layers of circuit boards is not particularlylimited to three and circuit boards may alternatively be arranged in twolayers by omitting the third support member and the third circuit boardor as another alternative be arranged in four layers if additionalcircuit boards and support members are used.

Again, while first and second card slots are arranged in the aboveembodiment, only a single card slot that can accommodate a thick typecard may alternatively be arranged. Then, the card slot can receive anycard so long as it conforms to an appropriate set of the PCMICA standardand the overall space requirement for the portable computer can besignificantly reduced.

The first and second card slots need not necessarily be arranged in twolayers and may alternatively be arranged side by side on a samehorizontal plane. They may still alternatively be so designed as toaccommodate cards conforming to an applicable standard other than thePCMCIA standard.

Finally, the present invention is not limited to book- ornotebook-shaped portable computers and may be applied to other portableelectronic apparatuses such as word processors.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details, representative devices, andillustrated examples shown and described herein. Accordingly, variousmodifications may be made without departing from the spirit or scope ofthe general inventive concept as defined by the appended claims andtheir equivalents.

What is claimed is:
 1. A compact electronic apparatus comprising:asubstantially rectangular housing having a peripheral wall; a cardstorage section having an insertion opening arranged on the peripheralwall and formed in a size capable to store an function expansion cardhaving the largest permissible dimensions conforming to a givenstandard, for selectively storing one of function expansion cards havingdifferent dimensions conforming to said standard; and a connectorconforming to said standard and arranged within the card storagesection, for connection with the expansion card stored in the cardstorage section.
 2. A compact electronic apparatus comprising:asubstantially rectangular housing having a peripheral wall; a first cardstorage section having an insertion opening arranged on the peripheralwall and sized so as to be capable of storing a function expansion cardhaving the largest permissible dimensions conforming to a givenstandard, for selectively storing one of function expansion cards havingdifferent dimensions conforming to said standard; a first connectorconforming to the standard and arranged within the first card storagesection, for connection with the expansion card stored in the first cardstorage section; and a second card storage section having an insertionopening arranged on the peripheral wall and sized so as to be capable ofstoring predetermined one of function expansion cards having dimensionsconforming to the standard; and a second connector conforming to thestandard and arranged within the second card storage section, forconnection with the expansion card stored in the second card storagesection.
 3. A compact electronic apparatus comprising:a housing having aperipheral wall; first and second circuit boards arranged in the housingand facing each other by a distance; a card storage section having aninsertion opening formed in the peripheral wall, for storing a functionexpansion card inserted through the insertion opening, a part of thecard storage section lying between the first and second circuit boards;a connector arranged on one of the first and second circuit boards, forconnection with the expansion card stored in the card storage section.4. A compact electronic apparatus according to claim 3, which furthercomprising a metal frame arranged in the housing and defining the cardstorage section.